Making various angle fittings or bending tubes has been a practice for many years. In some applications, long sweeping bends are used where the lowest possible pressure drop in the bend is desired. In other applications the space available, or the necessity to lie close to a right angle corner prompts the manufacturers to reduce the bend radius of the tube.
The use of castings, and the like, has become commonplace. This is because the stretching required to bend most tubing or piping around the outside of the bend, or the compression that is required of the pipe wall material in the inside radius of the bend limits the radius of the bend to some multiple of the tube diameter. In many important cases a large savings in cost would be possible if it were possible to approximate the small bend radius of a casting or machined port fitting with a tubular fitting.
An example of this situation is the use of large numbers of what are called "Banjo" fittings. A "Banjo" fitting has a body which looks a little like a Banjo, in that a stem, to which tubing is attached, extends from a circular end with a hole in the flat circular face of the circular end. This emulates the fret and string arm of a banjo extending from a circular sound box. Banjo fittings also require a bolt, through its center, through a hole in the circular end, to attach the "Banjo" fitting to the port. The fluid passage way is provided by drilling out the arm, and drilling out the center of the bolt. A hole is cross-drilled through the shank of the bolt to allow the fluid to enter the drilled out portion of the centerline of the bolt. Sealing, usually accomplished by a washer shaped gasket, is required between the banjo body and the port and the bolt head. The high cost of a "Banjo" connector is justified by the extensive work and material required to manufacture one. The use of "Banjo connections" has been worldwide for so many years and is eloquent testimony to the benefits which are gained by being able to make very small radius bends which are afforded by a "Banjo" connection.
A "straight-out" connection, and a bend in the pipe or tubing being connected is much less expensive, and much more reliable. If it were not for the routing advantage of a "Banjo" type connection, it is doubtful that any "Banjos" would be used at all.
The means disclosed herein provide a method of achieving the "Banjo" routing advantage, without having to also pay the high cost of a Banjo connection.
It is the object of this invention to provide a tube-like structure which achieves a very small bend radius.
Another object is to provide a complete family of fittings.
Heretofore difficult to obtain advantageous benefits may be more easily and inexpensively gained.
A more clear understanding of the means herein disclosed may be had by referring to the figures and discussion of the figures.